Estimating the number of prions in yeast cells

Cole, Diana J. and Morgan, Byron J. T. and Ridout, Martin S. and Byrne, Lee J. and Tuite, Mick F.
(2004)
Estimating the number of prions in yeast cells.
Mathematical Medicine and Biology, 21
(4).
pp. 369-395.
ISSN 1477-8599.
(The full text of this publication is not available from this repository)

Abstract

Certain yeast cells contain proteins that behave like the mammalian prion PrP and are called yeast prions. The yeast prion protein Sup35p can exist in one of two stable forms, giving rise to phenotypes [PSI+] and [psi(-)]. If the chemical guanidine hydrochloride (GdnHCl) is added to a culture of growing [PSI+] cells, the proportion of [PSI+] cells decreases overtime. This process is called curing and is due to a failure to propagate the prion form of Sup35p. We describe how curing can be modelled, and improve upon previous models for the underlying processes of cell division and prion segregation; the new model allows for asymmetric cell division and unequal prion segregation. We conclude by outlining plans for future experimentation and modelling.

Item Type:

Article

Additional information:

This is a core paper from a BBSRC-funded project Stochastic Models for Yeast Prion Propagation for which the principal investigators are Morgan, Ridout and Tuite (Biosciences). Cole & Byrne are postdocs. It is an important extension of earlier work by Morgan, Ridout & Ruddock (Biometrics, 2003) because it incorporates the asymmetrical cell division of the yeast species involved, and the resulting unequal segregation of the prions between mother and daughter cells. The new model leads to very different estimates of the average number of prions per cell, which is the key parameter of interest. Recently I have done further work on the numerical aspects using numerical inversion of Laplace transforms (not yet submitted).